Concealed Cisterns

Concealed Cisterns

A concealed cistern saves space and opens up a range of creative design options. If your client is short on space or looking to give their bathroom a sleek, minimalist feel, then a concealed toilet cistern is a choice worth considering. Justin Felix reports.

The bathroom, along with the kitchen, is the most commonly used room in any home, yet it is typically one of the smallest. It makes sense then that making the most of every square inch is crucial, not only for improving access and usability, but for allowing the maximum amount of space for regularly used amenities such as showers, baths and basins. This is especially important in apartments and units, which have seen significant reductions in size in recent times.

As the name suggests, a concealed cistern is hidden, either by being mounted inside a wall (in-wall), behind a wall (in-duct), in a ceiling, or within a cabinet or vanity unit. Concealed cisterns boast thin profiles to help them fit into narrow spaces in wall cavities.


Concealed cisterns have long been the preferred choice in commercial spaces such as hotels, bars and shopping centres; however, their benefits and aesthetic appeal are now becoming more highly sought after in residential bathrooms across the country.

The technology is not commonplace in Australia as yet; however, it has been around a very long time.

“It is the standard in Europe and has been for many years. For example, another manufacturer, Geberit is celebrating 50 years of concealed cisterns this year,” Rod Luker National Sales Manager Viega Australia says.BYRON

“When it comes to concealed cisterns, Australia is approximately 40 years behind many other countries; however, different countries have different installations. Australia has traditionally preferred exposed cisterns.”

This might be about to change though. While costs, comfort and functionality are all important, style is still top consideration for architects and clients alike, and without the right design aspects a product will not be specified.

With concealed cisterns, once completely installed, all you see is the flush plate, leaving a clean, sleek look, which is very much on point with common trends in homes and apartments around the country. Flush plates can either be attached to the cistern, or installed some distance away. They come in a variety of styles and colours to complement almost any bathroom design and because they’re mountable wherever’s convenient, cisterns that use a remote flush button are ideal for people with special needs or for those with limited mobility.

With constant improvements in innovation and technology, the dynamics of how toilets flush in recent years has dramatically improved, meaning these types of cisterns work just as efficiently as a regular cistern.

“Traditional cisterns use simple mechanical actuators only, whereby concealed cisterns can be operated by the same method or by Bowden cable, which then allow for remote placement of the flush plate,” Rod says.

“They can be retrofitted, usually by enclosing the cistern inside a fabricated duct in front of the wall (pre-wall). Viega’s Mono Slim system has an installation depth of only 8cm, which means it is ideal in stud walls or in front of masonry walls.”

There’s a general perception that concealed cisterns are always more costly or complicated than normal cisterns, although this often isn’t the case. The cost and ease of installation, in many situations, is likely to be comparable with what you’d expect with an exposed, close coupled cistern. Provided the decision to install a concealed cistern is made prior to the walls going up, it’s relatively straight forward, as explained by research and development manager GWA Caroma Dr Steve Cummings.

“When we first brought concealed cisterns over to Australia we spent a lot of time working out optimum installation solutions for them. We faced some complexities because unlike traditional cisterns, they go inside a wall. With exposed cisterns all you have to do is supply the water and outlet, connected to the wall or floor.

“There’s a lot of preparation work that needs to come first from other tradesmen because the framework must go in before the wall goes up and it has to be done right. It’s so important to get the installation correct and make sure it’s trouble free because major problems can arise with it being behind the wall.

“We’re also seeing cisterns going into ceilings because of ease of access. We had to develop special flush pipes using hydraulic solutions to accommodate those,” Steve says.

There’s also a perception that concealed cisterns will be more difficult to access and service than normal cisterns (particularly because they’re embedded inside the wall), although this concern’s mostly unfounded if your client is opting for a reputable brand. In most cases, these cisterns are designed with ease of servicing very much in mind, and a licensed plumber can typically service a concealed cistern within minutes, not hours.

Let’s take a look at some of the more reputable options on the market place.


For Viega’s Mono Slim cisterns there is a wide range of designer/architectural flush plates. There are no pans in this range.

“With the Viega Mono Slim cisterns, there is not as much access to the cistern as plumbers might be used to with a conventional cistern. However, they will quickly become familiar with the layout and will find servicing is simple. Viega’s focus is on providing a slim-line, dual-flush cistern that’s easy to install and use,” Rod says.

“Ease of installation is a major point of difference. The mounting plates on the cistern and on the frame enable simple assembly, plus the water supply connection comes completely pre-assembled. It means the connection to the feeder pipe is possible from outside, without opening the cistern.”

Viega Mono Slim cistern 2

Read the installation and service instructions. Contact Viega ( and/or Rogerseller ( for further assistance.

The Viega concealed cisterns have a 4 star WELS rating. Warranty details:

–       cistern body                                   10 years

–       mechanism and valves                 3 years

–       flush plates                                     3 years

–       sealings                                         12 months

–       availability of spare parts                 15 years

With the Viega concealed cistern solution (Mono Slim) there is a large array of designer flush plates to suit any décor. They’re designed to match a wide array of ceramics and taps and come in a choice of short or long, chrome, stainless steel, plastic or glass.


Since launching the first concealed cistern in 1964, Geberit has gone on to install over 60 million cisterns worldwide.

Geberit provides architects freedom of design, allowing for the creation of sleek, contemporary and elegant bathrooms. With more than 10 different button designs and 30 colour options there is a solution to suit any bathroom.

All Geberit cisterns have a 3 or 4 star WELS rating, and a dual flush system help considerably reduce water usage and can be paired with any approved wall hung or back to wall toilet pan of the same rating.

Viega concealed cistern 2 Geberit

Geberit Kappa under counter concealed cistern for back to wall and wall hung pans are ideal for under counter, under window and in vanity installation where the height of the cistern is less than 900mm. Moreover you have got flexibility with the location of the flush plate. Depending on the situation you can have it front or top operated which is unique to the Geberit under counter cisterns. All cisterns are WELS rated and come with 10 years manufacturer’s warranty for yours and your clients’ peace of mind.

Being the slimmest in-wall cistern on the market, the Sigma75 concealed cistern for Back to Wall and Wall Hung pans is the ideal choice for small bathrooms where space is at a premium, for both renovations and new builds. Once installation is complete all you see is a very elegant and sleek flush plate, paired with the pan of your choice. The functional parts of the toilet (plumbing, cistern, valves) are hidden behind the wall.

An extended 10 year warranty, 25 years spare part supply availability guarantees peace of mind. Geberit also provides technical support to architects for easing the specification process, as well as ongoing project support to ensure simple and successful installation.


Caroma’s Invisi Series II cisterns feature patented technology allowing them to be serviced through the button panel, so there is no need to remove tiles or wall coverings during a service.

A 4.5/3 litre dual flush plastic cistern, the Invisi Series II is suitable for inwall, under counter, induct and inceiling applications. The cistern features a number of contemporary button design options with concealed fixing that are pneumatically operated for ease of operation and installation. The push buttons can be activated remotely up to 4m from the cistern, ideal for care and custom applications.

Caroma_InvisiII_behindwall_Poster copy

The cistern incorporates Caroma Smartflush water saving technology and the cistern, bracket and specially designed waste pipe can be installed in a standard 90mm metal or timber stud wall application. The cistern is adjustable to 6/3 litre dual flush and is guaranteed not to leak when installed by a certified plumber in accordance with installation instructions. It should be installed with any Caroma or Fowler Pan.

Innovative Smartflush technology is built into the entire+ Invisi Series II range which Caroma claims can save up to 35,000 litres of water per household per year (compared to 11L single flush toilet suite). Smartflush is proven award winning technology, featuring a WELS 4 star water rating.



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